Yojijukugo 四字熟語
Yojijukugo (Japanese: 四字熟語) is a Japanese lexeme consisting of four kanji (Chinese characters). English translations of yojijukugo include "four-character compound", "four-character idiom", "four-character idiomatic phrase", and "four-character idiomatic compound". It is equivalent to the Chinese chengyu.
The definition of yojijukugo is somewhat murky since the Japanese word jukugo (熟語, literally "ripe/mature/popular word") can linguistically mean "compound", "idiom", or "phrase".
Yojijukugo in the broad sense simply means any Japanese compound words consisting of four kanji characters. In the narrow or strict sense, however, the term refers only to four-kanji compounds that have a particular (idiomatic) meaning that cannot be inferred from the meanings of the components that make them up.
Examples:
Once In A Lifetime Opportunity - 一期一会
Referenced from Wikipedia: https://en.wikipedia.org/wiki/Yojijukugo
